006
AXUS74 KHUN 152047
DGTHUN
ALC033-043-049-059-071-077-079-083-089-095-103-TNC051-103-127-172100-
Drought Information Statement
National Weather Service Huntsville AL
247 PM CST Thu Feb 15 2018
...Recent Rainfall Leads to Improvement in Drought Conditions...
Synopsis...
According to the Drought Monitor valid Tuesday, February 13th, 2018,
Severe Drought (D2) conditions no longer remain in northern Alabama
or southern Middle Tennessee. Locations previously under a D2
designation are now categorized in Moderate Drought (D1). Locations
that were previously under a D1 designation are now categorized as
Abnormally Dry (D0). Essentially, a one-category improvement was made
across the area.
Officially, D1 conditions exist across much of Northeastern Alabama,
encompassing much of Jackson and Dekalb Counties, the northern two-
thirds of Madison County, and much of central and eastern Limestone
County. Southern portions of Cullman County are also included in
this designation as well. Elsewhere, D0 conditions encompass most of
the remainder of northern Alabama, with the exception of the
southwestern half of Franklin County and small areas in western
Colbert and Lauderdale Counties, where there is no drought
designation.
In southern Middle Tennessee, far southern portions of Franklin
County are in D1, including a very small area in southeastern Lincoln
area. Elsewhere, D0 conditions are present.
Note: Precipitation and other conditions (streamflows, soil
moisture, etc.) that determine drought designations each week for
the U.S. Drought Monitor are based on data that end at 6 AM CST each
Tuesday. So, any precipitation that occurs after the 6 AM cutoff is
not factored into drought designations for that week, but will of
course be factored into designations for the following weekly
issuance. Also, it is important to remember that the designation of
drought categories is a process that utilizes numerous data from a
variety of sources on multiple space and time scales, which includes
precipitation, soil moisture, streamflows, groundwater, various
drought indices, and local drought impacts, just to name a few.
Summary of Impacts...
State and local declarations: The Alabama Department of Economic and
Community Affairs (ADECA) Office of Water Resources has no current
drought declarations in effect. However, the Drought Monitoring and
Impact Group within ADECA is scheduled to meet on February 21st, and
will make any necessary state drought declarations at that time. For
further information about the ADECA Drought Designations and
Planning, see the link near the bottom of the page.
The Keetch-Byram Drought Index (KBDI) available from the U.S. Forest
Service Wildland Fire Assessment System now shows values mostly under
200 across the area. However, a small area with values over 400 is
still centered over DeKalb County in northeastern Alabama. Values
over 400 are more typical for late summer or early fall and indicate
that lower litter and duff layers actively contribute to fire
intensity and will burn actively.
Climate Summary...
Precipitation deficits, which had begun to build in the Fall,
continued through January. During the month of January,
precipitation amounts were less than two inches across most of the
area, with the exception of parts of northwestern Alabama.
Precipitation deficits were around three to four inches in most
areas. In northwestern Alabama, deficits were a little lower, around
two inches at most locations. During January, temperatures wavered
back and forth from below to above normal, but below normal
temperatures certainly dominated in the region during the month,
beginning really in late December. In fact, temperatures have
averaged around three to five degrees below normal during the period.
The repeated intrusion of cold Arctic air masses into the region
brought not only cold air, but very dry air with low dew point
temperatures, leading to further evaporation of water from soils and
surface water sources.
However, the large scale pattern began to change in February. The
area is now experiencing repeated weather systems bringing beneficial
rains. So far for February, rainfall totals have been about two to
four inches above normal, with even higher totals around six or more
inches above normal in parts of northwestern Alabama. Huntsville
currently stands at 4.87 inches (2.52 inches above normal) for the
month and Muscle Shoals has received 6.24 inches (3.95 inches above
normal).
On longer time scales out to 90 days (reaching back to mid November)
precipitation deficits remain, which is part of the reason for
maintaining drought designations in the area. Rainfall deficits are
around four to six inches since mid November across much of north
central and northeastern Alabama and southern Middle Tennessee.
Meanwhile, deficits are only about an inch or less in some small
areas of northwestern Alabama, which is the reason for the removal
of drought designation in those areas.
Precipitation/Temperature Outlook...
Temperatures over the next week are expected to average well above
normal. A brief cool down will bring closer to normal temperatures on
Saturday. Otherwise, temperatures will likely average well above
normal, with daytime highs in the 60s and 70s and lows ranging from
the 40s on Sunday morning, to perhaps into the upper 50s to lower 60s
on Tuesday. Normal high and low temperatures for this time of year
are in the mid 50s and mid 30s, respectively. Precipitation for the
next week is expected to be above normal for this time of year, with
about 1.5 to 2 inches of rainfall expected.
The 8-14 Day Outlook from the Climate Prediction Center (CPC) valid
for February 23rd to March 1st strongly favors above normal
temperatures for the area. The outlook slightly favors above normal
precipitation for the area.
The Monthly Outlook for March from the CPC indicates no strong
signal regarding temperatures in the Tennessee Valley at this time.
As a result, the outlook indicates equal chances for below, near or
above normal temperatures. For precipitation, the March outlook
indicates that odds are tilted in favor of above normal
precipitation.
The latest Seasonal Outlook from the CPC for the March through May
period favors above normal temperatures and slightly favors above
normal precipitation.
Hydrologic Summary and Outlook...
Seven-day streamflow averages across the area experienced
significant degradation into early February, but have since shown
recovery. Some rivers were around the 10th percentile of their normalflow for this time of year into the first few days of the month, but
after recent heavy rains have at least temporarily experienced
significant rises. In fact, some rivers went into minor flood stage
recently. Due to heavy rainfall over the last week, weekly average
streamflows are at or above the 90th percentile in most rivers.
However, values have fallen over the last few days from recent highs.
Lake and river levels along the Tennessee River have been unaffected
by the drought that developed during the winter. Due to recent
rainfall, many lake levels, including those along the Tennessee River
are operating above the normal guide curve for this time of year.
According to the CPC, the latest daily soil moisture rankings
indicate that soil moisture values have begun to recover in the area.
As of early February, soil moisture rankings were in the 20th to 30th
percentiles. However, the latest data as of February 14th now
indicates closer to normal conditions, with slight surpluses of soil
moisture noted for portions of northwestern Alabama. Other soil
moisture analyses from the North American Land Data Assimilation
System (NLDAS) and NASA SPoRT Land Information System indicate a
significant improvement even in deeper layer soils (depths up to 2
meters).
The U.S. Geological Survey (USGS) groundwater well site in Cullman
County shows that groundwater levels fell below the daily median
value in mid-December and remained below normal levels until the past
week. Water levels are now about 12 feet above normal. Water levels
at the USGS site in Lawrence County averaged near to slightly below
normal from late December into early February, but have since risen
about two feet above normal.
The outlook for the next week is for improved conditions as rainfall
totals for this time of year are expected to be above normal.
Next issuance date...
Since Severe Drought (D2) conditions are no longer present in the
area, the next drought statement will be issued when drought
designations change significantly, which may occur with next week`s
update. Otherwise, a statement will be issued within the next month.
&&
Related Web Sites...(use lower case)
U.S. Drought Monitor webpage: http://droughtmonitor.unl.edu
Climate Prediction Center: http://www.cpc.ncep.noaa.gov
For information about Alabama Drought Declarations, visit:
http://www.adeca.alabama.gov/divisions/owr/pages/default.aspx
For information from the Alabama Forestry Commission, visit:
http://forestry.alabama.gov
Wildfire information from the Alabama Forestry Commission:
http://forestry.alabama.gov/fire_totals.aspx?bv=1&s=4
Radar estimated precipitation amounts can be obtained here:
http://water.weather.gov/precip
Streamflows are obtained from the USGS here:
http://waterwatch.usgs.gov/index.php
Lake levels for the Tennessee River can be obtained here:
http://www.tva.com/Environment/Lake-Levels
Soil moisture levels from the NLDAS can be found here:
http://www.emc.ncep.noaa.gov/mmb/nldas/drought
USGS groundwater well site information for Alabama:
http://waterdata.usgs.gov/al/nwis/current/
?type=gw&group_key=county_cd
Acknowledgements...
Some data used in this statement were provided by the U.S.
Geological Survey, the U.S. Forest Service, the Tennessee Valley
Authority, and the States of Alabama and Tennessee.
Questions or Comments...
For questions or comments on the drought, please contact:
National Weather Service Huntsville
320A Sparkman Drive
Huntsville, AL 35805
Phone: 256-890-8503
sr-hun.webmaster@noaa.gov
$$
KDW